Chitsetts



Jne 8 1926.

Filed Sept. 24, 1921 QJ 0 0 5 5 6 3 9 9 la lo o i o o )a O m j OAI O O O w M1 e 6 O O MO O5 Y. w L6 o www@ af /0 /v 9 9 No/w v3 5 VV /o 5 Patented June E, 1926.

UNITED STATES PATENT OFFICE.

THOMAS MIDGIJEY, OIF HAMPDEN. AND RALFI-I B. NAYLOR, 0F SPRINGFIELD, MASSA- CHUSETTS, ASSIGNORS TO THE FISK RUBBER COMPANY, OF CHICOPEE FALLS, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

TREATMENT 0F RUBBER ARTICLES.

Application filed September 24, 1921.

This invention relates to improvements in methods ot vulcanizing pneumatic tire casings. The present invention embodies specitic features ot a broader invention claimed in our Patent No. 1,394,928. granted October 25, 192i. This application is tor the purpose of covering a species, the genus and additional species of which, as well as the present species, have been fully disclosed in such patent.

The new method is carried out by applying heat to the inside ot a tire casing while leaving the outside of the casing exposed, in other words while the outside of the casing is not contined by molt s but on the contrary is exposed to an unheated fluid. The latter may in some cases be under pressure as unheated compressed air. This tluid pressure will prevent the blowing due to entrapped gases of the rubber covering ot the casing which is on the outside while the heat is being applied to the casing through the carcass or fabric portion which is on the inside ot the casing.

For a more. complete disclosure of the invention reference is made to the accompanying drawings in which Fig. l is a sectional view of a tire casing in which the stippled portion represents in a. general way the approximate degree ot partial vulcanization which may be given to the tire casing while the heat is applied to it from the inside.

Fig. 2 is a like view but showing by the stippling how the tire may be completely vulcanized after the molds have been closed on the covering rubber and heat applied through them to the tire casing.

Fig. 3 is a sectional and detail view of a vulcanizing pot in which this particular species et invention can be carried out to advantage.

'Io carry out the invention a completely built but unvulcanized pneumatic tire easing may be mounted on a core. The heated core applies heat locally to the inside of the tire casing. In this manner the heat may be applied to the inside ot the casing while the outside is exposed to the relatively cooler atmospheric fluid at normal or higher pressure. It is convenient to apply the heat through the core but it can of course be applied in other ways, for example in any otl Serial No. 503,020.

the ways as by heated Huid, it being known in the art how fluids may be confined to the inside of the casing.

For a better understanding I will describe how the improved method may be carried out in connection with the apparatus shown in Fig. 3.

In this ligure is shown a heater fitted up with means for maintaining separation ot the mold members as long as desired or until the regional or partial vulcanization through the carcass as indicated in Fig. l is completed. i

The heater comprises a cylinder 50 mounted on a casting 5l, supported on a Jfoundation 52. To cylinder 50 is secured a head 53 with inwardly projecting lugs 54 under which a removable cover 55 is held. Movable through the foundation and the casting 5l is a hydraulic plunger 56, under which water pressure is introduced by any suitable means. A table 57 is carried on the flanged top of plunger 56. By controlling the water pressure under the plunger the table may be raised and lowered, and a pile ot molds and tires placed on the table can be pressed with any desired torce against the cover 55. Leakage of water past the plunger 56 is prevented by stutling boxes 58 and 59. Provision is made, as by aninlet 60, and outlet 61, for furnishing compressed air, steam, or water to the inside of the heater. All the above parts are old and well known in the art and need not be ydescribed further.

The tire casings are mounted on internally chambered ring cores. These cores may be the ones on which the casings were constructed. Hollow cores such as core 13 it the tire casing is of the type having inextensible beads, may be formed of a plurality of sections held together by suitable means in a well known manner. Provision is made for the circulation of steam through the several hollow sections by any suitable steam connections. It the tire easings are of the clincher or extensible type the hollow cores may be integral having a partition wall between adjacent inlet and outlet passages for steam or heating fiuid tothe interior.

Connection is made to the hollow interior of the cores through flexible pipes as by an inlet pipe 62 connected tothe top core by a short pipey 63. The chambers. of the several cores are joined by flexible tubes 64, and the bottom core is connected to an outlet by a flexible tube 65. In this manner the conneet-ions of inlet pipe and outlet pipe to each coreprovides Afor a circulationin the cores;y By this circulation the cores may be maintained at a desiredtemperature so as to apply heat to the interior of the tire casing while the outside,.ofecthecasing is ex;- posed.

Surrounding eachf core.` is a, split mold composed `Otan upper section Gland a lower section 68. These sections are guidedrelative. to each other by dowels 69 fastened m the-lower section and running, in, holes'in theupper. section. Each section hasan .1nwardly projecting annular lug70 by which the sections of each mold are. `heldapart as willbe l.describir-id.. The forming faces; of the moldsections are: shapedto give the. desired form tothe'tire andmay be provided with the usual.y raised and depressed portions to give a design as indicated in Fig. Qalthough suchpattern has not been shown in Fig. 3. ,Y

Fittinglbetween -tlanges of the cores and lugs. 70 of the moldsare. double wedgesfl, which when held `outwardly will hold the mold sections apartl a.. distance out of. contact` withthe, casingwaccording to-the` designof the wedges. :71, andwill position the coremidway between them.` These wedges `formpart ofywhat maybe termed aftoggle unit. One toggle unit is provided for each of the split molds, andpreferably there are three wedges, `equally spaced circumfereir tially, to each unit. Each wedge isy pivoted by a pin to a .pair of arms72 which lstraddle an inwardly entendinglug on the. wedge. The otherends, of these; arms are pinned to a lug on head 73. Head is providedwith arilange 7 t, which serves as an `abutment to prevent the. arms 72 swinging upwardly' beyond thev position shown. In this position the arms are slightly higher than the, line of theiry pivots. on hea-d4 7 3, andhence, yonce they have beenplaced in this position, the pressure, exerted by the mold sections on l the wedges will prevent thel arms swinging downwardly past the linel of] their, pivots and the breaking ofthe toggleth'us'tormed.

The thickness off' head, 73. is preferably such .that when the. molds-and toggle units are stackedontopzof one another aslight bellfc-ra-nks v7 7 and whose topis arranged to abut `against the lowest head `73.- The other endfof'each bellfcranln is connectedby an link 78 to another bell-crank 79 pivoted to the table 57. rlhe lower end of bell-crank 79 is formed into a tubular sleeve 80 in which runs a spring pressed pawl 8l. The outer end of this pawl is adapted to engage a depending lug 82 vattached to casting 5l. Then the parts are inthe position shownin the figure-thc pile of molds reaches nearly to the cover, `and in this type of heater the mold pressure lor the tin al vulcanization is obtained `hytorcing the pile `against the cover by the hydraulic plunger 56. As the pluim'n er` is raised, the outer ends of pawls 8l catch under the lugs 82 and cause the inner ends of bel-Loranks 77 to be raised, thus raising the block y75, As this block abuts against the lowest head 73 the latter raised, swingingy toggle' arms72 past their dead center. lhen the toggle, is thus broken the weight of the molds piled on top of the bottom section of the lowest one will force the wedges of that one inwardly,` thus forcing the lowest head 7 3V upwardly until itzimpinges against the second from the bottom head. ln this manner the` breakingv of the toggles proceeds successively from bottom, to top ol the pile. lf desired the spa-,ce between heads 73 may bey decreased by thickening the heads enough to contact :so that all the toggles will be broken substantially simultaneously by the raising Vofbloch 7 5, but the presenty construction isprefen able in this `instance where the 4molds are held out` of Contact with the casings, asrit avoids heavy shock due to the-simultaneous collapse of all the molds, which are very heavy. Itwill be noted that the molds/may be collapsed and thevulcanizing pressure applied without removing the cover from the heater. This. both saves time and. avoids cooling. ofthe molds andcasings withconsequent loss of heatand interruption in the mold manipulating means described the ,ini vention could be carried outby'openingthe heater and` applying the moldsrto the casings byk handcr-` other ways.r The apparatus described isfor convenience;

A. platef83 with a cutaway rport-ion,` 84; is placed on the, topof the pile of molds to allow pressure to be exertedby they pile against the cover 55 without injuring the pipe 62.

On the descent of the plunger dpawls 8lY willslip by lugs 82.011 account `oli'their spring mounting, If the plunger is raised with no molds up-onit or with a.pile not reachingto the to a of the heater therpawls will be engaged by the lug as described, and will break the toggles-off whatever units are supported ,by 'the plunger, buti will then tilt past the. lugs and' allow the plunger `to ascend freely.

lu carrying out our invention with this fern-'1 of apparatusthe cover is` removed. the table 57 brought near the top ci' the heater, and the lower half of the bottom mold laid on. A core, with a tire casing mounted thereon, is taken and a toggle unit sprung into position with the inner wedge surfaces engaging flange 66 of the core. This core and toggle unit is then laid on the mold, the lower part of the wedges engaging lugs 7() on the mold. thus securing registration of the core and mold but with the casing out of contact with the mold. The tubes and (Si are connected, and the upper section of the mold laid on, registration heing seemed by the dowels (39 as well as the action of the wedges which keep the mold out of contact with the casing. Subsequent toggle units, molds, casings, ind cores, are laid on in a similar manner and the top core connected with tube 63. The wedges 7l not only serve to keep the mold sections separated` but also to maintain the cores centralized. Then all t-he parts have been positioned the cover clamped down and heat applied through the pipes to the chambered portions of the ring cores. During this local or regional application of heat to the inside of the pneumatic tire casings the outside of the casings are exposed. This exposure may be to the air at atmospheric pressure and normal temperature. The outside of the casings may be subjected during this part of the process to the action of unheated compresed air to prevent blowing This blowing is likely to occur when the casing has enough rubber covering as in the tread and sidewalls of a large tire to cause any entrapped gases in the rubber to expand. lVith the heat applied to the inside of the casing while the outside or covering rubber is exposed to an unheated medium the tendency is to keep the covering rubber at a lower temperature than the carcass and thus the tendency for the entrapped gases to eX- pand isA lessened. The amount and condition of the rubber under act-ual manufacturing conditions however varies and for this reason we have described various ways of treating the outside while the heat is being applied to the inside of the casing.

By the methods described it will be noted that a vulcanized bond is made between the carcass and the tread but the rubber of the latter' is left, substantially free and unvulcanized so as to flow freely under the mold pressure, giving a particularly advantageous condition of the casing to form the non-skid design on the tread. l

In the practice of the particular invention described the principal advantages will be self evident. Instead of using compressed air the molds may be brought together with sufficient contact with the casings to prevent blowing. This may be accomplished by properly designing the holding wedges for such contact. The heads 73 in this instance may be designed to Contact one with another so as to cause the simultaneous breaking of the toggle units since there will be no substantial fall of the mold parts.

When it is desired to apply the full pressure of the molds to the tire casings for thc final vulcanization it is merely necessary to admit pressure under the hydraulic plunger. The upward motion of this plunger both withdraws the wedges from their operative position and forces the pile of molds againstthe lower side of the cover as described. The heating of the tire casings is then continued, either hy continuing the supply of steam to the interior of the cores, or by admitting steam or heated fluid to the inside of the heater, or by both. In the claims we have defined the invention both intended to be covered in this application, in its broader and in its preferred embodiments.

Having thus described our invention, we claim Vl. The method of vulcanizing pneumatic tires which comprises applying heat to the inner surface of a tire whose outer surface is exposed, and subjecting the outer surface of the tire to an unheated fluid.

2. The method of vulcanizing pneumatic tires, which comprises applying heat without pressure to the inner surface of a tire whose tread portion is exposed, and subject ing said tread portion to an unheated fiuid.

3. The method of vulcanizing pneumatictires which comprises applying heat through a substantially non-expansible core to the inner surface of a tire whose tread portion is exposed and applying compresed air to said tread portion of the tire.

(Je. The method of vulcanizing pneumatic tires which comprises applying heat without pressure to the inner surface of a tire whose outer surface is exposed and subjecting the outer surface to a fluid pressure sufficient to prevent the covering rubber from blowing.

The method of vulcanizing a tire casing comprising assembling the carcass and tread portions thereof, heating the assembled casing from the inside outwardly until the casing is partially vulcanized, subjecting the outside of the casing to a fluid pressure su'tlicient to prevent blowing of the tread rubber while the casing is being heated from the inside, and then completing the vulcanization.

6. The method of vulcanizing pneumatic tires which comprises applying heat without pressure to the inner surface of a tire before applying heat or forming pressure to the outer surface of the tire and then applying heat and molding pressure to the outside of the tire.

7. The method of Vulcanizing pneumatic tires which comprises applying heat without pressure to the inner surface of a tire until tire While the outer surface is subjected tor retaining pressure only and Without heat eXH cept that conducted. from the inside surface Vuntil the carcass is partially vulcanized, then subjecting the outer .surface to forming pressure and the Whole tire tc sufficient heat to complete its vulcanization.

9. The method of Vulcanizing pneumatic tircswhich comprises the steps of heating and partially vulcanizing the tire from the inside while preventing' the blowing oiE the rubberby applying pressure to the outer .surface of the tire, and then heating the tire from the outer side to further vulcanize it.

l0. The inethod oit vulcanizing pneuinatic vtires which coinprises the steps oi heatingV andipartially vulcanizingthe tire from the inside only While the tread portion is free from mold pressure, and subsequently applying` inold pressure to said tread portion.

ll. rl'he inethod of vulcanizinp; `pneumatic tires which comprises introducing' a healiina' fluid into the space Within the tire While p venting blowing oi: the rubber by applying;` fluid under pressure to the outer surface olf the tire.

l2. The method oit' vulcanizing pneumatic tires which comprises applying heat to the inner surface of a tire whose outer .surface is exposed, and applying a cooling fluid to the outer surface of the tire.

'13, The niet-hed ot vulcanizing pneumatic tires which comprises applying heat with out pressure to the inner surface oi? a tire whose tread portion is exposed, and applying a cooling fluid to said tread portion of the tire.

14. rlhe method of vulcanizing pneumatic tires which coniprises applying heat Without pressure to the inner surface of a tire Whose u tread portion is exposed, and applying coinpressed air to said tread portion of the tire.

THOMAS MIDGLEY. RALPH B. NAYLOR. 

